How to prevent other processes from running on instance-dedicated cpus

We are running a single-node PackStack for evaluation purposes. We are able to successfully pin VM instances to CPUs, but we noticed that other services and processes can run on those same cores dedicated to the VMs. We've discovered that Setting a VM instance to dedicated means the VM will run on a specific CPU core, but it does not prevent other openstack services from running on that core.

Is there a way to isolate a CPU core to only allow it to run VM instances that I want it to run, preventing interference from other services?

We are running RH OpenStack 12.